现在大部分的网络系统登录时，除了要求提供用户名、密码外还需要提供一个验证码。请用文件形式完成一个登录验证程序。程序要求用户输入用户名，密码以及随机的一个图片验证码，通过验证后在给定目录下找到用户文本文件，读取文件并将内容显示在窗口上，用户可以对文本进行修改和保存。此外，要求把用户信息（用户名和密码）保存在文本文件中；可以由管理员添加新用户；用户可以修改自己的密码。-Now most of the network system log, in addition requires a user name, password, outside also need to provide a verification code. Please complete the form of a log file verification process. Program requires a user name, password and a random image verification code is verified in a given directory to find the user a text file, reads the file and the content displayed in the window, the user can modify and save the text. In addition, requiring the user information (user name and password) stored in a text file　you can add new users by the administrator　users can modify their own passwords.